Our study of the biogenesis of mitochondria and chloroplasts will be continued. We will attempt to identify the major protein products of the organelle genomes and to follow their subsequent assembly into functional units of the membrane complex. Yeast mitochondrial ATPase synthesis will receive a major emphasis for further studying using mutant strains having altered ATPase activity. A gene-product relationship between the protein components of the ATPase complex and the mitochondrial DNA will be sought. In chloroplasts, the study of synthesis of ribulosediphosphate carboxylase will be continued with emphasis on the mechanism of synthesis of the large subunit of the enzyme and on the mode of assembly of the active enzyme from nuclear and cytoplasmic gene products.